hvy. those clearly look like bolts/nuts to me. if not, it is a very tall weld or possibly pop rivets. a weld,especially a tack weld would not stick up that much. if you look in the 6th pic after "photo gallery" it shows inside the muffler. on the last pic you can see what looks like a bolt head sticking out from the lower portion of the exit. however, i agree that there is still a possibility of that exhaust being stupid loud when/if that silencer comes out which does make it a pos.
edit: also, above the picture set there is a portion that says "highlights of this kit" and under that it says "removable silencer on muffler tip"